Recently retinoid analogs (vitamin A) have been shown to be potentially useful as cancer preventives. The retinoids also play pivotal roles in the visual process as well as in the function of the purple membrane, the proton pump of Halobacterium halobium. The proposed research emphasizes the application and development of our vinyl allene synthetic approach to vitamin A as well as to other target molecules. We have developed two methods for synthesizing vinyl allenes. Vinyl allenes can be thermally rearranged through a 1,5-sigmatropic shift of hydrogen to (3Z)-1,3,5-hexatrienes and the latter can be further rearranged through electrocyclization to 1,3-cyclohexadienes. We propose to carry out studies in the following areas: (1) Application of the vinyl allene approach to the synthesis of 11-cis-and/or the unknown 9, 11-cis, cis-retinals as well as other retinoids; (2) Examination of the Z yields E rearrangement of 11-Z-retinal and preparation of 11-Z-retinal with isotopic labels; (3) A scope study of the preparation and chemistry of vinyl allenes to further elaborate on the chracteristics and limitations of the approach. Other target molecules of this approach include substituted indanones, tetralones, benzosuberones, quinolines, isoquinolines and napthalenes.